Spark plug



Patented Dec. 25, 1928.

.UfN-,slirnn rijst-Aires CABL JOHAN ELIGIUS .ISAKSSOLL OF SRA'NGA, SWEDEN, ASSIGNOR 0F ONE'-HALIEv TO HUGO"THEODO'RE TILL'QUIST,' OF STOCKHOLM, SWEDEN.

SPARK PLUG.

Application led August 13, 1925, Serial My invention relates to a new and iinproved spark plug for internal combustion engines, and has for its object to provide a spark plug whose elect-redes will automatically keep clean and 'free Jfrom all incrustations, deposit of carbon and the like, that are apt to form on them during the running of the engine. According to the invention this object is atta-ined with very simple means, and without the use of any special rubbing devices or other movable parts, such as valves kor the like. The principle, whereupon the invention is based, is to provide the spark plug with a hollow chamber, which communicates with the combustion room of the engine by an opening, channel, pipe or the like, the spark-gap] being arranged right in front of and close to the said opening or the like or in the said opening itself in such a way that the electrodes are fiushed and cleansed by the currents of gas and air that .flow into and out of said hollow chamber during the compression and expansion strokes respectively of the piston.

This principle can of course be carried out in several Ways and the structure of the spark plug be modified in a corresponding way.

I have illustrated the invention by way of example in. the accompanying drawing, in which- Figure l is a section through a spark plug according to the invention;

Fig. 2 is a plan view of the spark plug in Fig. l, seen from the combustion chamber; and Fig. 3 is a. plan view of a modified spark plug, seen from the combustion chamber.

Similar numerals refer to similar parts throughout the several views.

Referring to Figures 1 and 2, the spark plug comprises in the known way a body 2 of insulating material, which is inserted in a metal casing l, to be screwed into the cylinder cover. The body 2 is secured to the casing 1 by means of the threaded cap 3. The body 2 carries in the known way a central electrode 5, which can be connected to the electric circuit by means of a terminal 4. The casing 1 carries the other electrode 6.

The new features of the inventionconsist therein, that the inner ends of the casing l andthe body 2 are formed in such a way that a. chamber 9 is enclosed between them. This No. 50,102, and in Sweden May 22, 1925.

chamber 9 can be formed in different ways, for instance as shown in Fig. l by providing the inner end of the casing l with a` radial flange 1l directed towards the body 2 and separated from the latter by a narrow circular slot 7. ln this flange l1 an opening or channel 8 is made right opposite the spark-gap between the electrodes 5 and 6, which are bent towards each other in a way to bring the spark-gap right in front oi the said openincr 8.

During the compression stroke of the piston, combustible mixture is pressed through the opening 8 and the slot 7 into the chamber 9, sweeping these passages and the electrodes free from incrustaticns and the like. At the moment of ignition the pressure in the chamber 9 will also rise to the same height as the pressure in` the cylinder itself. As the pressure in the cylinder during the expansion stroke gradually decreases, the compressed mixture in the chamber 9 will continually flow out through the opening 8 and the slot 7, thus again flushing and cleaning the electrodes. Shortly before the end of the expan* sion stroke, usually after 85-90% of the stroke, the outlet valve begins to open. The pressure in the cylinder then rapidly decreases, which occurs during a disappearingly short time. The stream rises" and reaches a considerable strength, subjecting the electrodes to a third thorough cleaning.

During the flowing of gases into or' out of the chamber 9, a part of the gases flow through the narrow slot 7. The greatest part of the gases, however, will take the way of the least resistance, that is through the comparatively larger opening 8. The narrow slot 7 is, however, of great importance,ras the same affords a way out during the eXpansion stroke for incrustations, carbon deposits, etc., that now are blown out through the slot but otherwise would tend to accumulate in the chamber 9.

It a spark plug is used, whichis provided with several spark-gaps, as shown in Fig. 3, an opening 8 leading to the enclosed chamber should be provided in front of each spark-gap.

I claim Y A spark plug comprising a` metal sleeve adapted to be screwed into the cylinder head ot an engine, an insulated body positioned within Said sleeve forming a chamber thereoentrca-lly positioned opening therein oombetween, a flange formed with the lower end munoatng with said chamber and zu' 'angled of said metal sleevehavngaooneentro openn vertical alignment with said eleetodes. lo ing` therein through which passes Jhe lower In Witness whereof I have hereun'so set my 5 end of said insulated body, electrodes carried hand.

by the lower ends of sacl insulated body and meta-l sleeve, and said flange having an eo- CARL JOHAN ELIGIUS SAKSSON.V 

